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CCEA GCSE Biology > Photosyntesis & Plants - Practicals > Flashcards

Photosyntesis & Plants - Practicals Flashcards

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1
Q

Starch Test Explained

7 marks

A

Place the leaf in boiling water for 30 seconds – this kills it, stopping any further chemical reactions.

Place the leaf in boiling ethanol – removes the chlorophyll making the leaf paler in colour.

Dip the leaf in water – this softens it.

Spread the leaf onto a white tile and add iodine to test for the presence of starch.

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2
Q

Why do we place the leaf in boiling Ethanol during the Starch Test?

(2 marks)

A

Remove the chlorophyll making the leaf paler in colour.

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3
Q

What do we use to test for Starch?

1 mark

A

Iodine

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4
Q

Safety Rules during Starch Test

2 marks

A

Wear goggles throughout experiment.

Ensure Ethanol is not exposed to a naked flame.

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5
Q

Why shouldn’t you expose Ethanol to a naked flame?

1 mark

A

It’s highly flammable.

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6
Q

If a plant has Photosynthesised what will it test positive for?

(1 mark)

A

Starch

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7
Q

Starch Test Simplified

5 marks

A

Place Leaf in

  • Boiling Water 30 seconds
  • Boiling Ethanol
  • Dip in water
  • Spread on white tile and add iodine
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8
Q

Starch Test Results

3 marks

A

Starch present - iodine will change from yellow-brown to blue-black.

Starch absent - iodine will remain yellow-brown.

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9
Q

What will iodine tell us about a leaf?

1 mark

A

If it contains Starch.

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10
Q

If starch is present the iodine will change from yellow-brown to?

(1 mark)

A

Blue-black

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11
Q

If starch is absent the iodine what will happen to the iodine?

(1 mark)

A

It will remain yellow-brown/orange.

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12
Q

Colour of Aqueous Iodine Solution

1 mark

A

Yellow-brown/orange

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13
Q

How long should you place the leaf in water during the Starch Test?

(1 mark)

A

30 seconds

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14
Q

Why should you place the leaf in boiling water during the Starch Test?

(2 marks)

A

To kill it - stopping further chemical reactions.

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15
Q

Why should you dip the leaf in water after placing it in boiling Ethanol during the Starch Test?

(1 mark)

A

Soften it.

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16
Q

Destarching a Plant:

2 marks

A

Place Plant in the dark for at least 48 hours

  • during this time any starch will be removed or used.
17
Q

How can you Test if a Plant has been fully Destarched?

2 marks

A

Testing a leaf for starch through the Starch Test.

If iodine remains yellow-brown all the starch has successfully been removed.

18
Q

How many steps are there in the Starch Test?

1 mark

A

4 steps

19
Q

Before what is it important to Destarch a Plant?

1 mark

A

Before carrying out any photosynthesis practical.

20
Q

Investigating the Need for Chlorophyll in Photosynthesis: Procedure Simplified

(6 marks)

A

Destarch a Variegated Plant.

Make a drawing of the leaf.

Place the plant in bright light - 7 hours

Test the leaf for starch using the Starch Test.

Make another drawing of the leaf - showing areas of the leaf that tested positive negative for starch.

21
Q

Investigating the Need for Chlorophyll in Photosynthesis: Results

(3 marks)

A

Only the areas that contained Chlorophyll will Photosynthesise

Therefore test positive for starch.

Showing Chlorophyll is necessary for Photosynthesis.

22
Q

Investigating the Need for Chlorophyll in Photosynthesis: Procedure Explained

(6 marks)

A

Destarch a Variegated Plant - partly green and partly white.

Make a drawing of the leaf.

Place the plant in bright light - 7 hours

Test the leaf for starch using the Starch Test (4 steps)

Make another drawing of the leaf - showing areas of the leaf that tested positive + negative for starch.

23
Q

Variegated Plant

3 marks

A

Partly green and partly white - due to the presence of 2 kinds of plant tissue.

(no chlorophyll development in certain areas)

24
Q

How long should you place a plant in bright light when Investigating the Need for Chlorophyll in Photosynthesis?

(1 mark)

A

7 hours.

25
Q

Only what areas will Photosynthesise?

1 mark

A

Containing Chlorophyll.

26
Q

Investigating the Need for CO2 in Photosynthesis: Procedure

6 marks

A

Destarch a Plant.

Expose 1 leaf to Sodium Hydroxide = will absorb CO2 from the surrounding air.

Expose another leaf to water (control experiment) = will not absorb CO2 from the surrounding air.

Place the plant in bright light - 7 hours.

Test both leaves for starch using the Starch Test.

27
Q

A Destarched leaf exposed to Sodium Hydroxide will do what?

1 mark

A

Absorb CO2 from the surrounding air.

28
Q

Will a Destarched leaf exposed to Water absorb CO2 from surrounding air?

(1 mark)

A

No - will not absorb CO2 from the surrounding air.

29
Q

Will a Destarched leaf exposed to Sodium Hydroxide absorb CO2 from surrounding air?

(1 mark)

A

Yes - will absorb CO2 from the surrounding air.

30
Q

Investigating the Need for CO2 in Photosynthesis: Results

3 marks

A

Only the leaf that has been exposed to CO2 will Photosynthesis

Therefore test positive for starch.

Showing CO2 is necessary for Photosynthesis .

31
Q

Is CO2 necessary for Photosynthesis?

1 mark

A

Yes.

32
Q

Is Chlorophyll necessary for Photosynthesis?

1 mark

A

Yes.

CCEA GCSE Biology (33 decks)

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